The present invention relates to a semiconductor read only memory (ROM) system implemented with MOSFETs. The present invention relates, more particularly, to a read control circuit for the read only memory system.
In one type of the conventional read only memory system, the entire data read lines are precharged to conduct the data read operation. Thus, a considerably large current is consumed by the discharge from non-selected data read lines. In another type of the conventional read only memory system, only a selected data read line is charged via a charging element. In this conventional system, the row selection is conducted at the same time when the selected data read line is charged. Therefore, a direct current flows through the charging element and the selected memory cell. Thus, the power consumption is not satisfactorily reduced.
Accordingly, an object of the present invention is to provide a read control circuit for a semiconductor read only memory.
Another object of the present invention is to provide a read control circuit for a CMOSFET read only memory, which minimizes the power consumption at the data reading operation.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, the precharging operation is conducted only to a desired area, thereby minimizing the power consumption caused by the discharge. Furthermore, the data reading operation is conducted after the completion of the precharging operation, thereby preventing the occurence of the direct current through the selected memory cell.